The concept of treating water with a chemical such as bromine to kill bacteria in a body of water is known in the art. Bromine offers the advantage of being slow dissolving to enable a time release of the bromine as well as being free of odors associated with other biocides. Typically, bromine is supplied in solid form. In addition, the use of metallic ions to kill bacteria in a body of water is also known in the art. In general the bromine concentration in the body of water should be maintained within a certain range to be effective. That is, if the concentration of bromine in a body of water is to low the ability to kill microorganisms is reduced or lost. On the other hand if the concentration of bromine in the water is to high it can be harmful to those who use the body of water. Typically, when bromine is added in solid form it is activated with an oxidizer to form hypobromous acid (HOBr) which kills the unwanted organisms.
A metallic ion such as a silver ion is an effective bactericide for a body of water including recreational water such as swimming pools, spas, jetted tubs or the like and is a preferred material because it is generally easier and safer to use than other bactericides or algaecides. A further advantage of using a silver ion is that it minimizes the need for pH adjustment of the body of water. However, if the concentration of metallic ions in a body of water is to low the ability to kill microorganisms is reduced or lost. On the other hand if the concentration of metallic ions is to high it can be harmful to those who use the body of water.
Oftentimes it is desired to use two or more biocides to kill microorganisms in a body of water in order to more effectively kill a wider variety of different microorganisms in the body of water. One of the difficulties is that when bromine is used in conjunction with a metal ion the metal ion and the bromine interact to reduce the effectiveness of the metal ion in killing microorganisms, oftentimes to a level that renders the metal ion concentration ineffective to kill microorganisms, thus negating the reason for using the two biocides.
When bromine is used separately in a body of water the bromine concentration can be controlled by the periodic release of bromine to the body of water from a bromine donor. Similarly, when a metallic ion is used, such as a silver ion, is used separately in a body water the silver ion concentration in the body of water can be maintained by the periodic release of a silver ions into the body of water from a silver ion donor. However, when two or more biocides or disinfectants such as a metal ion disinfectant is used in conjunction with bromine the level of metal ions in the water can be adversely affected so that the level of metal ions becomes insufficient to provide for effective control of microorganisms in the body of water thus rendering the combination impractical. Thus, the advantage of having metal ions in combination with bromine for use in treating a body is water is lost since the bromine can reduce the metal ion concentration in the water to levels that are ineffective to rid the body of water of microorganisms that normally would be killed by the presence of the metal ions.
The present invention is a discovery that with the use of a chelating agent the concentration of bromine and the concentration of a metal ion can both be maintained within effective microorganism killing regions when placed together in the same body of water and that the level of bromine can be maintained at lower concentration levels without diminishing the biocidal aspect of the combination.